Contoured seat cushion comprised of honeycomb cores

ABSTRACT

An improved anatomical support apparatus including an upper substrate engagable with a body surface of a user, and a support substrate attached to the upper substrate. The upper substrate having a first honeycomb core formed of undulated strips of resilient thermoplastic material, thermal compression bonded together to form cell walls defining a plurality of contiguous regularly shaped cells. Each of the cell walls having an upper extremity and a lower extremity. Each upper and lower extremity of the first core forming either a planar or a contoured surface. The upper substrate further includes means for maintaining the first core in its expanded configuration. A stack having at least one support substrate attached to either the upper or the lower extremity of the first core. A support substrate including a second honeycomb core formed of undulated strips of resilient thermoplastic material, thermal compression bonded together to form cell walls defining a plurality of contiguous regularly shaped cells. Each of the cell walls of the second core having an upper extremity and a lower extremity. Each upper and lower extremity of the second core forming either a contoured or a planar surface. In addition, the support substrate also includes means for maintaining the second core in its expanded configuration. The first and the second cores being anisotropically flexible and capable of stabilizing and spreading a load exerted thereupon by the user of the support apparatus. 
     In a preferred embodiment the support apparatus comprises a seat cushion in which at least the upper substrate defines a contoured surface adapted to support prominences in the body of a seated user.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of our U.S. application Ser.No. 08/080,745 filed Jun. 22, 1993, now U.S. Pat. No. 5,444,881, whichis a continuation-in-part of our U.S. application Ser. No. 07/974,474filed Nov. 12, 1992, now abandoned, which is a continuation-in-part ofSer. No. 717,523, filed Jun. 19, 1991, our U.S. Pat. No. 5,180,619entitled "Perforated Honeycomb," which is a continuation-in-part of Ser.No. 446,320, filed Dec. 14, 1989, our U.S. Pat. No. 5,039,567 entitled"Resilient Panel Having Anisotropic Flexing Characteristics and Methodof Making Same."

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to anatomical support apparatus,and more particularly to mattresses and seat cushions having at leastone thermoplastic elastomeric honeycomb panel.

2. Description of the Prior Art

Substantially immobile people (i.e. wheelchair bound users) have a greatneed for support cushions that minimize the development of decubitusulcers (i.e. bedsores) that can occur during long periods ofconfinements to beds or chairs.

Traditionally, foam and gel-filled materials have been used in seatcushions to absorb shock, reduce pressure, and provide support for wheelchair users. There are many prior art seat cushions that are comprisedof a foam cushion encased within a washable covering, wherein the foamcushion is formed so as to provide a comfortable seating surface. Forexample, the foam cushion may have a cut-out or contact-free zone formedthrough it to reduce pressure on the user's spine, coccyx (i.e.tailbone), or ischial tuberosities, or to eliminate physical contactbetween the cushion and particularly sensitive portions of the user'sbody.

In other devices, the foam is specially tapered or shaped to enable theuser to easily rise from the seat. Shaping the foam in such cushionshelps reduce high pressure areas and positions the user for posturing,but only if the user's anatomy fits the contours of the shaped foam.High pressure points will still occur if the user has an anatomy thatdoes not conform to the contours of the shaped foam. This is frequentlythe case when the user is an amputee, or is improperly positioned on thecushion, or is changing positions on the cushion.

In yet other prior art devices, a gel or other fluid-like substancefills an impermeable sack which is disposed within or on a foamenvelope. The entire assembly is encased within a moisture resistantcloth, vinyl and/or urethane, or waterproof covering and placed on aseat as a seat cushion. In some cases the gel-filled cushion is formedwith contours or contact-free zones to relieve contact and pressure onsensitive portions of the user's body. For example, U.S. Pat. No.5,191,752 discloses a seat cushion formed from silicon dielectric gel isused in an equestrian saddle. The gel cushion, although somewhat shockabsorbent, is heavy and prone to damage from punctures and the like. InU.S. Pat. No. 5,201,780 a tri-layered mattress pad is disclosed. The padincludes a cover or casing containing an interior strata of a plasticfilm layer atop a fluid bladder layer supported on a foam layer. The padis designed to reduce the development of bedsores by reducing normal andlateral pressures and forces on the bed user. As discussed below, thereare disadvantages associated with foam and gel-filled materials.

One problem associated with gel materials is that they retain heat.During periods of continuous contact with a user's body, the temperatureand moisture in the contact areas between the gel-filled cushion and theuser's body also increases. An elevated gel material temperature causesuser discomfort and exacerbates any existing injuries (e.g. bedsores)the user may have. The moisture increase also creates an unsanitarycondition for the user because bacterial growth in the contact area ispromoted and the user's injuries are likely to become infected.

Secondly, gel-filled cushions disposed in the wheelchairs of athleticusers are especially uncomfortable. During outdoor athletic activity(i.e. during exposure to sunlight) or during periods of physicalexercise, the temperature of the gel material reaches and remains athigh levels. The gel material remains hot even when the user stopsexercising and is attempting to cool down. Also, in cold weather, thegel freezes into a solid or semi-solid state.

In a gel-filled cushion, the gel tends to move (i.e. spread) away fromthe area under load. The user of the cushion, or his assistant, isrequired to "knead" (i.e. push) the gel back into the proper locationbeneath the user's body. This is a tiring, difficult, and inconvenientactivity.

Another shortcoming of using gel-filled cushions is that the impermeablesack which contains the gel can have a hammocking effect on the user'sprominences. This causes high pressure zones beneath the protrudingareas resulting in sores or other injury.

Finally, gel-filled cushions are relatively heavy, and especiallyvulnerable to damage or destruction from puncturing.

In addition, there are shortcomings associated with foam materialswhich, for example, are susceptible to taking a compression set aftermany periods of use. It is typical, that after a prolonged period of usethe foam cells collapse and the support benefit of the cushion is lost.Also, foams cushions must be encased within impermeable coveringsbecause they readily absorb fluids. The foam cushion must be replaced ifincontinence or an accidental spill wets a cushion with a torn covering.

Some wheelchair cushions utilize pneumatic devices as a pressurerelieving system for reducing ischemic injury. U.S. Pat. No. 5,193,237,for example, discloses a pneumatic wheelchair cushion having a number ofseparate unattached air sacks arranged in a matrix. Reduced airflow andtherefore reduced air pressure is periodically provided within thecushion so that each air sack will have reduced pressure for apredetermined period of time. A self-regulating air distribution isprovided such that when the occupant shifts his/her weight so as toovercome the air pressure in a sack, the system automatically backflowsair into that particular sack thereby cushioning the user.

The disclosed wheelchair device is complex, and requires electricalpower and pressurized air. Such devices are overly complicated, costlyto acquire, and costly to maintain. Also, the air cushion device must befrequently adjusted, can be punctured, and is unstable for a user.

In addition, there are some prior art mattresses that include a matrixof air cells that are inflated and deflated to more evenly supportbodies and reduce the development of bedsores. In addition to the airsupply components (e.g. compressor, valving, tubing, etc.) thesemattresses also require a computer to constantly measure the resistancein each air cell and to control the reaction of each cell to pressureand load changes by varying the deflation and inflation in each cell.These devices are also costly, complicated, require adjustment, andsubject to puncture damage.

The prior art also discloses resilient honeycomb structures used inpersonal-use items. U.S. Pat. Nos. 5,134,790 and 4,485,568 discloseusing resilient honeycomb structures in the sole of shoes. Also, U.S.Pat. No. 4,422,183 to Landi et al. discloses a protective body shieldhaving a honeycomb structure constructed from a resilient flexiblematerial. Finally, U.S. Pat. No. 5,203,607 discloses an improved bicycleseat including a rigid shell supporting a foam layer having a pad ofthermoplastic elastomer honeycomb disposed within or thereon. In all ofthese devices, the honeycomb structures are not utilized in seatcushions and mattresses.

Thus, there is a need to provide an improved anatomical supportapparatus that maximizes pressure relief, stability, comfort,durability, maintainability, and weight, yet does not possess theshort-comings of the presently employed devices.

SUMMARY OF THE INVENTION

Objects of this Invention

It is therefore an object of the present invention to provide animproved anatomical support apparatus that provides improved pressurerelief and stability characteristics, significant compression setresistance, durability, low weight, and low maintenance properties.

It is another object of the present invention to provide an improvedanatomical support apparatus having at least one thermoplastic elastomerhoneycomb panel that conforms, supports, and stabilizes a wide varietyof sitting positions, user anatomies and disabilities.

It is still another object of the present invention to provide animproved anatomical support apparatus that is breathable to permitcooling of the user.

Another object of the present invention is to provide an improvedanatomical support apparatus that can be tailored to create the desiredcushioning and stabilizing characteristics without having to introduceelements such as foam, fluids or other elements which add cost or reducedurability.

Still another object of the present invention is to provide an improvedanatomical support apparatus constructed of materials that are fastdrying, and can be easily disinfected and sterilized by chemical wash,microwave, detergent, or other means.

Another object of the present invention is to provide an improvedanatomical support that has at least one flexible thermoplasticelastomeric honeycomb having at least one contoured surface engagablewith a body area of a user.

Briefly, an improved anatomical support apparatus includes a frame forsupporting the apparatus, an outer envelope and a resilient inner bodyencased within the envelope, both the inner body and the outer enveloperesting on the frame. The inner body including a first panel having atleast one honeycomb core, first and second facing sheets. The core isformed of undulated strips of resilient thermoplastic material, thermalcompression bonded together to form cell walls defining a plurality ofcontiguous regularly shaped cells. The first facing sheet is formed ofresilient thermoplastic material that is thermal compression bonded toan upper face of the core formed by upper extremities of the cell walls.The bonding is accomplished by simultaneously applying heat and pressureto the joinder of the first facing sheet and the core. The second facingsheet is similarly formed from resilient thermoplastic material and isthermal compression bonded to a lower face of the core formed by lowerextremities of the cell walls, the bonding being accomplished bysimultaneously applying heat and pressure to the joinder of the secondfacing sheet and the core. The core anisotropically flexes to stabilizeand spread the load exerted by the user.

In an alternate embodiment of the present invention, an improvedanatomical support apparatus includes at least one contoured substrateand at least one planar substrate attached to the contoured substrate.The contoured substrate includes a first honeycomb core formed ofundulated strips of resilient thermoplastic material, thermalcompression bonded together to form cell walls defining a plurality ofcontiguous regularly shaped cells. Each of the cell walls having anupper extremity and a lower extremity, and at least one of the upper andthe lower extremity forming a contoured surface. The contoured substratefurther includes means for maintaining the first core in its expandedconfiguration. The planar substrate is attached to one of the upper andthe lower extremity of the first core, and includes a second honeycombcore formed of undulated strips of resilient thermoplastic material,thermal compression bonded together to form cell walls defining aplurality of contiguous regularly shaped cells. Each of the cell wallshaving an upper extremity and a lower extremity, each of the upper andthe lower extremity forming a planar surface. In addition, the planarsubstrate also includes means for maintaining the second core in itsexpanded configuration. The first and the second cores beinganisotropically flexible and capable of stabilizing and spreading a loadexerted thereupon by said user of the cushion.

An important advantage of the present invention in that thethermoplastic elastomer honeycomb panel used in the construction of theapparatus is an anisotropic material having improved pressure relief,stability, compression set resistance, durability and low maintenancecharacteristics.

Another advantage of the present invention is that single or multiplethermoplastic elastomer honeycomb panels may be configured within theanatomical support apparatus to customize and individually tailor it foran individual user.

Yet another advantage of the present invention is that an anatomicalsupport apparatus can support and conform to a wide range of usersupport positions, user anatomies and disabilities.

Yet still another advantage of the present invention is that entire oronly portions of the anatomical support apparatus may be pressurized tocreate different support and stability characteristics.

Yet another advantage of the present invention is that the anatomicalsupport apparatus may be constructed from a perforated corethermoplastic elastomer honeycomb panel and perforated faces that isbreathable to allow perspiration removal and cooling of the apparatususer.

Another advantage of the present invention is that differentthermoplastic elastomer honeycomb core designs or multiple panels ofdifferent thermoplastic honeycomb core designs may be utilized tomaximize design flexibility of the improved anatomical supportapparatus.

Still another advantage of the present invention is that thethermoplastic elastomer honeycomb core is fabricated from recyclablematerials that are fast drying, and easily disinfected and sterilized.

These and other objects and advantages of the present invention will nodoubt become apparent to those skilled in the art after having read thefollowing detailed description of the preferred embodiment which iscontained in and illustrated by the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view illustrating a wheelchair having disposedthereon an improved anatomical support cushion constructed in accordancewith a preferred embodiment of the present invention;

FIG. 2 is a perspective view illustrating a thermoplastic honeycombpanel of the type utilized in the improved anatomical support cushionshown in FIG. 1, wherein the panel has a non-perforated honeycomb core;

FIG. 3 is a partial cross-section taken through the line 3--3 of thepanel illustrated in FIG. 2 to illustrate the structural characteristicsof one embodiment of the panel;

FIG. 4 is a partial cross-section illustrating an alternative embodimentof the panel illustrated in FIG. 2;

FIG. 5 is a perspective view of another thermoplastic honeycomb panel ofthe type utilized in the improved anatomical support cushion shown inFIG. 1, wherein the panel is shown with a non-perforated facing sheetbroken away to reveal a perforated honeycomb core, and also illustratedis a separate section of the panel having a perforated honeycomb core aswell as a perforated facing material;

FIG. 6 is a partially broken depiction of a thermoplastic honeycombpanel, similar to the panel illustrated in FIG. 5, communicativelycoupled to a bulb pump;

FIG. 7 depicts a force deflection comparison plot between a seat cushionutilizing foam or gel materials and an improved cushion having athermoplastic honeycomb panel of the present invention;

FIG. 8 illustrates the idealized honeycomb seating cushion designparameters;

FIG. 9 illustrates the buttressing effect of the cells of athermoplastic flexible honeycomb panel of the present invention whenloaded by a wheelchair user;

FIG. 10A through 10E are cross-sectional views of the cushionillustrated in FIG. 1 wherein alternative thermoplastic flexiblehoneycomb panel configurations are illustrated;

FIG. 11 is a perspective view of a flexible thermoplastic honeycombpanel of the type illustrated in FIG. 1, partially broken to show aflexible honeycomb core insert disposed on a conventional foam cushion;

FIG. 12 is a cross-sectional view of the panel illustrated in FIG. 11;

FIG. 13 is a perspective view of an improved anatomical support cushionhaving a foam layer and a plurality of independent flexiblethermoplastic honeycomb pad sections that are fitted into cavitiespre-formed within the foam layer;

FIG. 14 is a perspective view of an improved anatomical supportapparatus of the present invention used in a bed disposed on a standardhospital bed frame;

FIG. 15 is an enlarged perspective view of the bed including a mattresspad of the present invention; and

FIG. 16 is a cross-sectional view of the bed taken along the line 16--16of FIG. 15;

FIG. 17 is a perspective view of an alternate embodiment of the presentinvention including a cushion having at lease one contoured substratemade from a thermoplastic elastomeric honeycomb panel;

FIG. 18 is a partial sectional view of one embodiment of the cushionshown in FIG. 17, having a contoured upper substrate;

FIG. 19 is a partial sectional view of another embodiment of the cushionshown in FIG. 17, having a contoured intermediate substrate;

FIG. 20 is a partial sectional view of yet another embodiment of thecushion shown in FIG. 17, having a contoured upper substrate and astiffened intermediate substrate; and

FIG. 21 is a partial sectional view of still another embodiment of thecushion shown in FIG. 17, having a contoured upper substrate and afacing sheet disposed therein.

DETAILED DESCRIPTION OF THE EMBODIMENT

Referring now to FIG. 1 which depicts a conventional wheelchair 10having disposed thereon a removable improved anatomical support cushion12. As will be described in greater detail below, the cushion 12 isconstructed of at least one flexible thermoplastic elastomer honeycombcore panel built in accordance with the present invention. It should benoted that, although the cushion 12 is particularly well suited forwheelchair applications, the cushion 12 may be used in a variety ofother anatomical support applications (e.g., mattresses, automobile andairline seats, arm rests, seat belts, etc.).

Referring to FIG. 2 which illustrates a honeycombed panel structure 14constructed from thermoplastic elastomer materials. The panel 14includes a honeycomb-like core preferably made of bonded together andexpanded strips or ribbons 16 of plastic material to which facing sheets18 and 20 of perhaps heavier gauge material are thermocompressionbonded. The panel is an anisotropic three-dimensional structure havingpredetermined degrees of flex along the X, Y and Z axis. Each cell isformed, in part, by four generally S-shaped wall segments each of whichis shared by an adjacent cell. In addition, each cell shares a doublethickness wall segment with two adjacent cells.

Panel 14 has high tear and tensile strength and is highly resilient,with optimal compression load and shock absorption or distortioncharacteristics yet is extremely light weight. Selected combinations ofelastomer material, honeycomb cell configurations, core thickness andfacing material variables will determine the panel's characteristics ofsoftness or hardness, resilient recovery rate and rigidity or flex asrequired for a particular application. The facing materials can beselected from a wide variety of films, including thermoplasticurethanes, foams, EVAs, rubber, neoprene, elastomer impregnated fibersand various fabrics, etc. The manufacturing and fabrication of the panel14 is described in greater detail in our U.S. Pat. No. 5,039,567 andincorporated herein by reference.

FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG. 2. Asillustrated, each wall of the core will have a structure which resemblesan I-beam, as indicated at 22, and upper and lower faces 24 and 26,either or both of which may be deformed during a planarization operationas disclosed in our above identified U.S. Patent to stabilize thehoneycomb core and prevent the expanded strip from collapsing. The faces24, 26 are firmly bonded to the facing sheets 18 and 20. In addition, asillustrated in FIG. 2, each cell will be formed of four generallyS-shaped vertical wall segments 28 joined together with two wallsegments 30 and 32 of double thickness. With the top and bottom edges ofthese walls bonded to the upper and lower facing sheets 18 and 20 aunitary honeycomb panel is provided with no seams or separations.Because of the high integrity of the bonds between the core and facingsheets, the anisotropic features of the structure will be uniform andpredictable. In addition, as illustrated in FIG. 4, a multi-coredstructure may be built up as depicted at 34. Such structure can includedifferent core configurations 36 and 38 as well as different types offacing materials 40, 41, and 42. It will, of course, be appreciated thatwithin a single core cell, dimensions may be varied by changing thedimensions and/or spacings of the bonding ribs used during the build-upof the core stack.

FIG. 5 is a perspective view of a perforated core (or perforated cellwall) honeycomb panel 44. The panel 44 is broken into two sections, aleft hand section 45 and a right hand section 46 in order to more fullyillustrate alternative embodiments. The left half 45 shows materialhaving a perforated honeycomb core 48 and unperforated or solid facingsheets 49 and 50. The dashed lines 51 illustrate the normal fullcoverage of the top facing sheet 49.

The honeycomb core 48 is made from sheets of a selected gradethermoplastic elastomeric material that has been perforated such that amatrix of small holes 59 exists throughout. The sheets are compressionbonded together in spaced intervals staggered between alternating sheetsas described in our U.S. Pat. No. 5,039,567 and incorporated herein byreference. The resulting stack is then cut into strips which, whenexpanded, create a honeycomb network of elongated, generally hexagonallyshaped cells 52.

Each cell 52 of the honeycomb core 48 is defined by four generallyS-shaped wall segments, each interior wall of which is shared by anadjacent cell. The wall segments of each cell 52 include a singlethickness wall portion 54 and a double thickness wall portion 56.

The upper and lower faces 58 and 60 of the walls forming several cellsare deformed during a planarization operation as disclosed in ourabove-identified U.S. Patent to stabilize the honeycomb core and preventthe expanded strip stock from collapsing. Facing sheets 49 and 50, cutfrom sheets of resilient thermoplastic material, are then compressionbonded to the upper and lower faces 58 and 60. The addition of thefacing sheets 49 and 50 strengthens the core 48 and provides an amplesurface for adhering another panel or other material.

The right half section 46 of the panel depicted in FIG. 5 includes aperforated honeycomb core 47 similar to the left hand section 45 of thepanel, but has facing sheets 55 and 53 made of perforated material.Dashed lines 57 indicate the honeycomb pattern of the core 47 underneaththe top facing sheet 55. By perforating both the honeycomb core andfacings, the weight of the material is reduced while the resiliency andflexibility is increased. The weight is reduced because the perforationsreduce the overall quantity of the material comprising the honeycomb andfacings. Similarly, the flexibility is increased because there is lessmaterial to constrain each segment of the material from bending. Theresiliency, or ability of the structure to spring back to its originalform after being compressed, is also enhanced by virtue of theadditional passages through which air can return to fill the cells. Itwill be appreciated that the resilient but damped restorativecharacteristics of the structure make it an excellent absorber of shockwaves.

Referring now to FIG. 6 which depicts a pressurized honeycomb panel 62including a pump subsystem 63, and a perforated core honeycomb panelsubsystem 64.

The subsystem 64 includes a first facing sheet 66, a second facing sheet68, and a flexible perforated honeycomb core 70. The core 70 isdescribed in greater detail in our U.S. Pat. No. 5,180,619 which ishereby incorporated by reference. The core 70 includes cell walls 71with perforations 72 and is affixed to the inside surfaces of the firstfacing sheet 66 and the second facing sheet 68. The facing sheets extendoutwardly beyond the core 70 and are bonded together around theirperimeters as indicated at 74 so as to form an enclosed chamber 76 whichis hermetically sealed and adapted to contain a suitable gas. Forpurposes of illustration, the chamber walls are broken away as indicatedat 78.

In order to permit the gas contained within the enclosed chamber 76 tobe increased or decreased in volume or pressure, the pump subsystem 63is communicatively coupled to the chamber 76. The subsystem 63 includesa bulb pump 80 that is coupled via a conduit 81 to the chamber 76. Anexhaust valve 82 is installed in the conduit 81 and allows the chamber76 to be vented to atmosphere. As will be appreciated by those skilledin the art, the selected addition or subtraction of gas into or out fromthe enclosed chamber 76 will result in a change in the force-dissipatingcharacteristics or shock absorbing capabilities of the panel in responseto applied forces such as illustrated by the arrow 83.

Honeycomb, and particularly anisotropic honeycomb has a number ofbeneficial characteristics for anatomical support applications ingeneral, and particularly for mattress and seating applications wherethe disadvantages of more traditional materials, such as gels and foams,become particularly unacceptable. Important characteristics for generalseating, and especially for wheelchair seating materials, includepressure relief (load spreading), comfort, stability, durability, lowmaintenance, light weight, and low transmissibility (good impactisolation).

Pressure relief is particularly important for wheelchair seatingapplications because local pressure spots, within the range of 60-80 mmHg (1.16-1.55 psi), quickly develop into sores on relatively immobilepeople. Seat cushions having honeycomb panels of the present inventionare ideal for use as wheelchair cushions because such panels haverelatively flat force deflection characteristics.

FIG. 7 shows a force-deflection plot 84 of a foam cushion compared to aforce deflection plot 86 of a cushion having a honeycomb panel of thepresent invention. The modulus (i.e. compressive force divided bydeflection) over a 15 to 55 percent deflection range, for foam isdepicted by a line 88. The modulus, over the same deflection range, forhoneycomb of the present invention is depicted by a line 89. The figureshows that the modulus for the honeycomb panel cushion is approximatelyone-fourth that of the foam cushion. Pressure variations, in thehoneycomb panel cushion caused by anatomical features (i.e. protrusions)of the wheelchair user, are approximately one-fourth those of foamcushions. Thus, a wheelchair user's anatomical protrusions are lesslikely to cause local high pressure spots and bed sores if the user sitson a honeycomb panel cushion of the present invention rather than on atypical foam cushion.

The characteristic of honeycomb that makes it an ideal in this area isthe relatively flat "plateau region" that characterizes the honeycombpanel's force-deflection property. In FIG. 8, a force-deflectionrelationship or line 90 is plotted for honeycomb constructed inaccordance with the present invention. The force-deflection line 90 ismeasured over a useable deflection range 91 that ranges from 0 to nearly80 percent deflection. It will be noted from the figure that there arethree distinct regions in the force-deflection line. There are tworegions where the modulus (i.e. slope) of force over deflection is verysteep, that is, the modulus one region 92 and the bottoming region 94.However, in the plateau modulus region 93, which extends over theplateau region deflection range 95 (i.e. roughly 8-75 percentdeflection), the slope of the line is relatively flat. If the honeycombconfiguration is properly selected such that the weight of thewheelchair user divided by his sitting area places the user in themiddle of the plateau modulus region 93 then local increases ordecreases in cushion deflection caused by the user's anatomical featuresdo not appreciably change the pressure exerted on the user. In otherwords, the user's anatomical protrusions do not create the local highpressure spots which could lead to bedsores and other similarulcerations. In engineering terminology, the compressive modulus ofhoneycomb constructed in accordance with the present invention, is lessover the plateau region 93 than the compressive modulus of typical foamor gel seat cushions.

Pressure relief by itself is not sufficient to make a satisfactorywheelchair seating cushion because stability must also exist. The bestpressure relief system is ineffective if during maneuvers or motions theuser tips or slides off the seating area of the cushion. FIG. 9 depictsthe self-aligning and supporting characteristic of honeycomb panels ofthe present invention. A user profile 96 is illustrated as beingdisposed onto a seat cushion 97 constructed from a honeycomb panel ofthe present invention. As depicted at 98, in response to the user load,the honeycomb cells tend to align themselves in a buttressing mannerwith the applied load, even as the load shifts. This effect can beenhanced by selecting a softer honeycomb for the topmost layer of thecushion, in effect creating a buttressed pocket for the lateral portionsof the thighs and buttocks. In addition, the anisotropic flexingcharacteristics of a single and double walled honeycomb provide enhancedstability (i.e. greater shear modulus) in the direction of the doublewalls. Depending on the needs and activity level of the user, thisorientation can be changed to provide the most effective support. For atypical user (this would be support in the fore and aft orientation tohelp prevent slumping or sliding off the cushion.

Another principal benefit of the honeycomb cushion characterized by thepresent invention is the ability to tailor it (e.g. varying materials,varying cell configuration and size, etc.) to create the desiredcushioning and stabilizing characteristics. The honeycomb panel may betailored either by adding other components, e.g. fluids, or by notintroducing elements such as fluids, foam, or other elements which addcosts and reduce durability. As an example, one or more layers of thehoneycomb cushion can contain perforated cells walls, which in effectcreates a configuration that breathes like an open cell foam but withoutthe foam's porosity and resultant susceptibility to absorbing liquids. Aperforated cell honeycomb can provide performance benefits such asquicker recovery from loading and a lower modulus with greaterdisplacement capability than the same configuration in enclosed cellhoneycomb. In conjunction with the inflation device and valvearrangement, as illustrated in FIG. 6, the perforated cell cushion withsealed edges can be pressurized to increase the air cushion effect insituations where this is beneficial. Note that a perforated honeycombair cushion is much more shear resistant, thus more stable, than anequivalent conventional air cushion.

Compression set resistance and resistance to repeated loadings, i.e.good material memory, are also important benefits of a seat cushionhaving honeycomb of the present invention. The compressive resistanceand recovery of both honeycombs and foams comes from bending of the"strut elements" which comprise their geometries. These strut elementsare more uniform in honeycomb than foam. Because of this greateruniformity, the compression set resistance and recovery is greater inhoneycomb than in foam. In addition, closed cell (faced) honeycomb hasthe additional resilience afforded by the integral trapped air creatingan air spring. Comparison testing of honeycomb and foam configurationsused for seating applications in which comparable samples were loadeddaily for 16 hours on and 8 hours off, revealed 1.5 to 2.0 percentcompression set for the foams compared to less than 1 percent forhoneycombed seating cushions of the present invention.

Also, the honeycomb seating cushions of the present invention are lightweight and require low maintenance. Weight is an important factor duringtransfer operations of the wheelchair into and out of a vehicle. Lowmaintenance and ease of cleaning are important because a wheelchaircushion cannot necessarily be quickly replaced if incontinence or anaccidental spill wets the cushion. Honeycomb panels of the presentinvention typically have solid facing sheets which act as washablebarriers that will not absorb water like foam cushions. Nor arehoneycomb panels susceptible to puncturing like some of the gel- filledcushions currently available.

Referring now to FIG. 10A through 10E wherein are depicted crosssectional views of an improved cushion in accordance with the presentinvention. FIG. 10A depicts a single flexible honeycomb panel 100encased within a vinyl or similar covering 102. The panel 100 isconstructed in accordance with the referenced U.S. patents and includesa non-perforated core 104, and facing sheets 103 and 105. Although asingle unperforated cell wall honeycomb panel is illustrated it will beappreciated that in the alternative a single perforated core honeycombpanel may be used as an alternative embodiment.

In an alternate embodiment not shown, the panel 100 could be removedfrom the covering 102 and either or both of the facing sheets 103 and105 perforated in a predetermined pattern. The area of the perforationscould be varied depending on the specific requirements of the user. Forexample, if a particular user needed greater cushioning for a certainregion of his body, the facing sheets for the cushion area supportingthis body region could be perforated. In this manner, the cushionapparatus can be individually customized to a user's specific needs.Perforating the cushion in a predetermined manner to accommodatespecific user requirements can be utilized for any embodiment of thepresent invention.

Referring to FIG. 10B which illustrates two perforated core honeycombpanels 106 and 108 encased within the covering 102, it should be notedthat honeycomb panel 106 is of different size cell construction thanhoneycomb panel 108, panel 108 having larger cell walls as illustratedin the figure. Further, although an embodiment with two differenthoneycomb panels has been illustrated it is possible to construct thecushion with two equally sized honeycomb panels. Alternately, differenttypes of honeycomb panels may be mixed according to the supportingproperties desired. For example, panels having different core designs(i.e., cell size, configuration, or materials) may be used. Also, anon-perforated cell wall honeycomb panel may be configured with aperforated cell wall honeycomb panel and vice versa. In addition, two ormore layers of honeycomb panels may be stacked in accordance with thedescriptions referenced earlier in our prior U.S. patents.

Referring to FIG. 10C which depicts an improved cushion having apressurized honeycomb panel 110 encased within the covering 102. Asdescribed earlier, the pressurized honeycomb panel 110 is comprised of aperforated honeycomb core 112, encased within a non-perforated facingsheet covering 114, that is in communication with a pump subsystem 116,via a conduit 118. In this manner, the pressurized honeycomb panel 110may be alternatingly pressurized to vary the support characteristics ofthe honeycomb core 112 contained within.

Referring to FIG. 10D which illustrates a multi-layer cushion having aplurality of honeycomb panels contained within a covering 102. In thisparticular embodiment, the pressurized honeycomb panel 110 is attachedto a non-perforated core honeycomb panel 120. Alternately, twopressurized honeycomb panels could be used with each panel system havingdifferent properties, i.e. different materials and/or cellconfigurations and sizes. In addition, each individual panel could havedifferent stiffnesses in different areas. For example, a stiffer areawould be placed in a forward area where the user's legs and thighs aresupported, and a softer area placed beneath the buttocks area. This canbe accomplished by constructing the panels with more than one cellconfiguration. In another embodiment not depicted in the figure, thepanel 120 could have perforated cells walls rather than non-perforatedcell walls as illustrated. Finally, although two honeycomb panels aredepicted, more than two panels could be employed, and the arrangement ofpanels could have a pressurized panel disposed between non-pressurizedpanels or a non-pressurized panel disposed between two pressurizedpanels.

FIG. 10E illustrates a multi-layer apparatus 164 having a two-layerpanel subsystem 166 disposed onto a pump subsystem 168. The panelsubsystem 166 includes pressurized honeycomb panels 170 and 172. Eachpanel has perforated cell walls 176, 178 and facing sheets 170a and170b, 172a and 172b. Each facing sheet has a plurality of perforations176a and 176b, and 178a and 178b. The two panels 170 and 172 are coveredby a permeable covering 174 that permits the passage of fluid (e.g. air)from the panels 170 and 172. The pump subsystem 168 includes a baseplate 180 having a channel 182 formed therein so that the channel can becommunicatively coupled, via a conduit, to a pump or fan device 188. Aplurality of exhaust ports 184 are formed in a surface of the base plate180 and intersect with the channel 182. The pump device 188 is alsocommunicatively coupled to a fluid source (not shown) via an inputconduit 189.

Fluid (e.g. air) is drawn from the fluid source, in the directionindicated by the arrow 190, by the pump device 188. Fluid is passedthrough the conduit 186 into the channel 182 and out through the ports184 of the base plate 180. The fluid passes through the contactingpermeable covering 174 and into the panel 172, via the perforations 178bin the facing sheet 172b. The fluid passes from the panel 172 to thepanel 170 via the perforations 178, 178a, and 176b. Finally, the fluidexits the panel 170, via the perforations 176 and 176a, out through thepermeable covering 174. The fluid exiting from the apparatus cools andcomforts a user sitting thereon.

It will be appreciated that only one panel or even additional panels maybe utilized to maximize the comfort and support for a particular user.Also, a perforated covering may be used in lieu of the permeablecovering 174. Further, the pump device 188 may draw from a variety offluid sources other than the ambient environment.

Although not illustrated, an alternate pump subsystem may include a pumpdevice communicatively coupled to a porous conduit. The conduit beingsimilarly disposed as the base plate 180 or, in the alternative, theconduit could be disposed underneath the uppermost panel (e.g. betweenpanels 170 and 172) for supplying cooling air through panel 172 to theuser.

FIG. 11 illustrates a partially broken view of yet another alternativeembodiment of an improved cushion 122. The cushion 122 includes ahoneycomb core 126, facing sheets 128 and 129, a foam pad 130, allencased within a covering 124. As more clearly illustrated in FIG. 12,the honeycomb core 126 is disposed on top of the foam 130. Although anon-perforated honeycomb core is illustrated, a perforated cell wallhoneycomb core could be utilized, or alternatively a pressurizedhoneycomb panel system could be utilized. FIG. 13 illustrates stillanother embodiment of the seat cushion 122 wherein a plurality ofcavities 132 and 134 are disposed on the surface of the seat cushion122. Within each cavity a separate honeycomb core insert 136 is placed.The particular inserts illustrated in FIG. 13 are non-perforated cellwall honeycomb core inserts with top and bottom facing sheets 138, 140.In the alternative, the core inserts 136 could be constructed fromperforated cell wall honeycomb panels or pressurized honeycomb panels.Although only two core inserts have been illustrated in the figure, aplurality of core inserts could be installed on numerous locations onthe surface of the cushion to vary the support characteristics of thecushion to conform to the individual needs of the wheelchair user. Thus,core inserts of varying stability and stiffness could be interchanged toindividually tailor the support and pressure relief characteristics ofthe cushion. Although not illustrated, in a multi-layer cushionapparatus, the core inserts could be removable from any of the panels(i.e. in a three layer apparatus, the core insert could be removablefrom the second panel).

A logical extension of the anatomical support cushion described above isa pad used for supporting the buttocks, shoulders, head, and other partsof the anatomy of a reclining or sitting user. FIG. 14 is a perspectiveview of a bed 142 supported on a standard hospital bed frame 144, thebed 142 having carrying straps 146 disposed at numerous location aroundits periphery. The bed 142 of the present invention is not limited touse in a hospital environment but may be used in other human carefacilities (e.g. nursing, convalescent, retirement homes, etc.) or otherenvironments.

FIG. 15 depicts an enlarged perspective view of the bed 142 illustratedin FIG. 14, but with the carrying straps 146 omitted for clarity. Thebed 142 includes a mattress 150 with a mattress pad 148 dispose thereonand which covers the entire mattress 150. It will be appreciated,however, that the mattress pad 148 could be sized such that it coversonly a portion or discrete portions of the mattress 150. As illustratedin the cutaway portion, the mattress pad 148 includes a honeycomb corepanel 152 having a facing sheet 154 and a facing sheet 160 (not shown).The honeycomb core panel 152 can be configured in ways different thanthe type illustrated, i.e. perforated cell walls, unfaced honeycombcore, etc.

FIG. 16 is a cross-sectional view taken along the line 16--16 of FIG.15, and depicts the construction of the mattress pad 148 and mattress150. The mattress 150 includes a foam core 156 encased within a mattresscovering 158. The mattress pad 148 includes the honeycomb core panel152, facing sheets 154 and 160, and a pad covering 162 encasing thepanel 152 and facing sheets 154 and 160.

FIG. 17 is a perspective view of a contoured seat cushion 200 which isan alternate embodiment of the seat cushion 12 depicted in FIG. 1. Seatcushions, fabricated from at least one panel of flexible thermoplasticelastomeric honeycomb and having a planar or non-contoured surfaceengagable with a body surface (e.g., thighs, buttocks) of a user,provide pressure relief, stability, durability and washability. However,a planar engagable surface does not provide as much positioning andposture control of the user as does a non-planar or contoured engagablesurface.

The contoured seat cushion 200 includes an upper layer 206, anintermediate layer 208, and a bottom layer 210. Each layer is fabricatedfrom thermoplastic elastomeric honeycomb in the manner described above,and the construction of each of the cells of the honeycomb panels of thelayers is also as described above. Each cell wall of each layer has anupper extremity and a lower extremity (best seen in FIG. 18-21). Theintermediate layer 208 is sandwiched between the layers 206 and 210 andis attached to the lower extremity 252 and the upper extremity 258 ofthe upper layer 206 and the bottom layer 210, respectively.

In addition, a surface 205 formed by the upper extremities 250 of thecell walls of the upper layer 206 has been sculpted or shaped to providethe distinctive illustrated contoured features depicted in FIG. 17. Thedirectional terminology adapted for the cushion 200 is also illustratedin FIG. 17. A direction 201 is designated as "left", a direction 202 is"right", direction 203 is "rear", and a direction 204 is "front".

A central rear portion of the surface 205 of the cushion 200 has beenformed with a coccyx cutout depression region 212 which preventspressure buildup on a sensitive coccyx (i.e. tailbone) which cannot takeas much pressure as other areas of the user's body. An ischial dishingdepression region 214 is formed forward of the cutout region 212. Theischials are a pair of bones forming the dorso-posterior portion of thepelvis; the interior part of the human pelvis upon which the body restsduring sitting. A trochanter shelf is a slightly concave region formedin the surface 205. One shelf is disposed to the left (shelf region 218)and one shelf is disposed to the right (shelf region 216) of the ischialdishing region 214. The trochanter is a projection on the proximal endof the femur.

An adductor shelf region 228 is an upwardly curved region formed on thesurface 205 and is disposed along the center line of the seat cushion200 and spaced generally equidistant from the left and the right edgesof the cushion 200. A left abductor region 220 is an upwardly curvedregion formed on the surface 205 and disposed to the left of the region228. Similarly, a right abductor region 222 is formed on the surface 205to the right of the region 228. Leg troughs 224, 226 are formed on thesurface 205 and flank the region 228 on the left and the right sides,respectively. Posturing or positioning problems include abduction oradduction of the legs (the legs are either too far apart or too closetogether).

The ischial dishing region 214, the abductor regions 220, 222, and theadductor region 228 perform positioning or posture control of a user ofthe contoured wheelchair seat cushion 200. The abductors and adductorsare essentially side bolsters and a pommel, respectively, designed toprevent the user's legs from sliding around and prevent the user's kneesfrom banging together. The dishing region 214 allows the ischials of theuser to engage the surface 205 of the cushion 200 without restrictionand sink into a natural, anatomic position thereby alleviating thetendency for posterior tilt, or slouching of the pelvis. The reardishing in the back is designed to evenly support the user's pelvis sothat it remains upright and straight. This .provides a stable foundationand a greater balance for the user who has limited or no use of hislower truck muscles.

The ischial dishing region 214 and the abductor regions 220, 222 andadductor region 228 also provide for increased stability for the user ofthe seat cushion. As described above, seat stability is particularlycritical for wheelchair users. A cushion which provides a stable seatingplatform enhances the user's ability to wheel and turn the wheelchair bygrasping the wheels, to get in and out of the chair, and to performother dynamic movements. A cushion which provokes non-stability or afear of falling from the chair will inhibit the user's range ofmovement. Thus, the dishing region 214 and the adductor region 228 andabductor regions 220, 222 provide the lateral support that is needed forthe user under dynamic conditions.

As described above, the nature of a thermoplastic elastomeric flexiblehoneycomb panel is that it enhances the pressure relief capability ofthe cushion. This pressure relief capability is further enhanced bycontouring or shaping the surface 205 that is engageable with the bodysurface of the wheelchair user. For example, the ischial dishing region214 increases the contact area with the buttocks and upper thighs of theuser. Since the user's weight is distributed over a larger area, thecushion material undergoes less deflection to conform to the body,therefore, the resistive force is less. This translates into reducedpressures over a wider contact area. The coccyx cutout region 212prevents pressure build up on the sensitive tailbone which cannot takeas much pressure as other areas. Also, the shelf regions 216, 218 cradlethe trochanters (the bony protuberances extending from the upper part ofthe femur) for added support which relieves pressure from the ischials.Further, the shaped leg troughs 224, 226 increase the contact area withthe user's thighs thereby distributing the user's weight over a largerarea and more evenly distributing the pressure on the cushion.

In addition, using an elastomeric flexible material avoids hammocking.Hammocking is defined as a suspension of the bony prominences of theuser on the surface of the cushion preventing total conformation of thecushion to the user's body, thereby preventing complete pressureequalization. Using an elastomeric material allows the upper or contactsurface 205 of the cushion to stretch in response to pressure from thebony prominences of the user, thereby distributing the pressure over alarger area.

Also, the wheelchair cushion 200 is extremely durable. Because of theexisting contour, the material in the cushion experiences lesscompressive deflection and fatigue, while remaining resilient longer.

However, it should be noted that the cells of the honeycomb panel of thecushion 200 could be oriented as shown by the cells in the region 230 oras shown by the cells in the region 240. That is, the double wallportions 234 of the cells in the region 230 may be aligned in thefront-rear direction. Alternately, the double wall portions 244 of thecells in the region 240 may be aligned in the left--right direction. Ineither case, the walls 241 or 231 of each of the cells are perforatedwith perforations 242 or 232. Perforating the cell walls of the cells ofeach of the layers 206, 208, 210 enables the seat cushion 200 to belightweight and washable, and also permits cooling air to pass beneaththe user thereby providing a comfortable seating surface. In addition,the open or bare faced honeycomb layers allow moisture to drain throughthe cushion thereby keeping the uppermost layer 206, i.e. the layerengagable with the skin of the user, dry.

FIG. 18 is a partial sectional view of a contoured seat cushion 201having a generally similar construction to the cushion 200 (FIG. 17).The cushion 201 includes the upper layer 206 having an upper extremity250 and a lower extremity 252. A contoured or non-planar surface isformed by the upper extremity 250 of the cells of the upper layer 206.In contrast, the upper extremity 254 and the lower extremity 256 of theintermediate layer 208 is planar. Similarly, the upper extremity 258 andthe lower extremity 260 of the bottom layer is planar. The figure, theupper extremity 254 of the layer 208 is attached to the lower extremity252 of the upper layer 206. Similarly, the upper extremity 258 of thebottom layer 210 is attached to the lower extremity 256 of theintermediate layer 208. The three layers 206, 208, 210 are encasedwithin, but not bonded or attached to, a stretchable, breathable andpermeable casing 209, thereby permitting the attached layers 206, 208,210 to be removed and washed and cleaned apart from the casing 209. Thecasing 209 may be formed with vents (not shown) to enhance itsbreathability and permeability. It should be noted that wetness ormoisture (from user incontinence or otherwise) drains through thecushion, via the unfaced layers 206, 208, 210, and the permeable casing209, to keep moisture away from the user's skin.

FIG. 19 is a partial sectional view of a contoured seat cushion 203,which is generally similar to cushion 200 (FIG. 17) The upper extremity254 of the intermediate layer 208 forms a non-planar or contouredsurface. The upper extremity 254 is attached to the lower extremity 252of the upper layer 206 thereby causing the upper extremity 250 of theupper layer 206 to be disposed in a non-planar or contoured manner.Thus, a body portion of the user will engage a contoured or non-planarsurface. It will be appreciated, that the bottom layer 210 could have acontoured upper extremity 258 in addition to or in lieu of the extremity254. Alternately, the lower extremities of either the intermediate layer208 or the bottom layer 210 could be contoured thereby causing the upperextremity 250 of the upper layer 206 to be non-planar.

FIG. 20 is another embodiment 207 of the contoured seat cushionillustrated in FIG. 17. In this embodiment three bolstering orreinforcing regions 264, 266, and 268 are formed in the intermediatelayer 208. In the regions 264, 266, 268, as compared to the otherportions of the cushion 207, the cell size may be reduced, or thethermoplastic material comprising the cell walls may be made from astiffer material (e.g. higher durometer) or, the cell walls may beconstructed from ribbons having greater thickness. The effect is toprovide a stiffer region for supporting the upper layer 206. In thismanner, for example, if the regions between the reinforcing regions wereconstructed of a less stiff or more flexible material, then the user andhis bony prominences would sink between the reinforcing regions whichwould perform the same functions as a upwardly contoured bolster orother similar device. Also, the cells in the bolster regions are lessprone to collapse or roll over as the user leans to one side. It will beappreciated as an alternate to the illustrated embodiment, thereinforcing regions could be placed in either the upper or the bottomlayers.

FIG. 21 is a sectional view of yet another embodiment of the contouredseat cushion in FIG. 17. In this embodiment, a thermoplastic elastomericfacing sheet is disposed between the upper and the intermediate layers206, 208. The facing sheet 270 is formed with a plurality ofperforations 272 to allow air and fluid to flow from one layer to theother. For example, cooling air can flow from the bottom layer to theupper layer and ultimately to the user. It will be appreciated, that thefacing sheet could be disposed between the intermediate and the lowerlayers.

It will also be appreciated that the cell walls of any of the layers ofany of the embodiments 201, 203, 207 of FIG. 18, FIG. 19 and FIG. 20respectively could be unperforated.

Although preferred, and alternate embodiments of the present inventionhave been disclosed above, it will be appreciated that numerousalterations and modifications thereof will no doubt become apparent tothose skilled in the art after having read the above disclosures. Forexample, the anatomical support cushions may be configured in anyappropriate shape, with multiple panels and with various combinations ofperforated and non-perforated core panels, and with core walls and/orface sheet perforations the number and/or hole size of which aretailored to achieve desired damping characteristics. It is thereforeintended that the following claims may be interpreted as covering allsuch alterations and modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. An improved seat cushion comprising:a) at leastone contoured substrate includingi) a first honeycomb core formed ofundulated strips of resilient thermoplastic material, thermalcompression bonded together to form cell walls defining a plurality ofcontiguous regularly shaped cells, each of said cell walls having anupper extremity and a lower extremity, at least one of said upper andsaid lower extremity forming a contoured surface, and ii) means formaintaining said first core in its expanded configuration, said firstcore being anisotropically flexible and capable of stabilizing andspreading a load exerted thereupon by a user of said cushion; b) atleast one planar substrate attached to one of said upper and said lowerextremity of said first core, said planar substrate havingi) a secondhoneycomb core formed of undulated strips of resilient thermoplasticmaterial, thermal compression bonded together to form cell wallsdefining a plurality of contiguous regularly shaped cells, each of saidcell walls having an upper extremity and a lower extremity, each of saidupper and said lower extremity forming a planar surface, and ii) meansfor maintaining said second core in its expanded configuration, saidsecond core being anisotropically flexible and capable of stabilizingand spreading a load exerted thereupon by said user of said cushion; andc) whereby predetermined prominences of said user's body are received insaid contours formed in said contoured surface.
 2. An improved seatcushion as recited in claim 1, wherein said means for maintaining ofeach said first and said second honeycomb cores includes:(a) aplanarizing thermal compression deformation of a first face of said coreformed by said upper extremity of said cell walls.
 3. An improved seatcushion as recited in claim 2, wherein said means for maintaining ofeach said first and said second honeycomb cores includes:(a) aplanarizing thermal compression deformation of a second face of saidcore formed by said lower extremity of said cell walls.
 4. An improvedseat cushion as recited in claim 3, wherein said means for maintainingof each said first and said second honeycomb cores further includes:(a)a first facing sheet of said resilient thermoplastic material bonded tosaid first face.
 5. An improved seat cushion as recited in claim 4,wherein said means for maintaining of each said first and said secondhoneycomb cores further includes:(a) a second facing sheet of saidresilient thermoplastic material bonded to said second face.
 6. Animproved seat cushion as recited in claim 5 wherein said cell walls ofat least some of said cells of said first core have perforationstherein.
 7. An improved seat cushion as recited in claim 6 wherein saidcell walls of at least some of said cells of said second core haveperforations therein.